EP 0 874 382 discloses a rotary-operation type electronic component incorporating a push switch—see e.g. FIGS. 1 and 2. A revolving contact-points board 2, which functions as movable contact-points for the rotary encoder and the push switch, is attached on a fitting substrate 1—the fitting substrate 1 constituting fixed contact-points. The revolving contact-points board 2 is provided with a round operation knob 3 fixed on it for driving, and is held revolvable by a pillar shaft 4 inserted through a center hole 2A. The revolving contact-points board 2 is slidable in a horizontal direction too on the fitting substrate 1 in the front-rear direction, and is being pushed to the front by a push back spring 5. A pulse signal is generated in accordance with the revolution of the operation knob 3.
It is a drawback that the push back spring 5 is positioned external to the rotary member since it thereby occupies extra space in the front-rear direction. Thus the push back spring 5 affects the total size of the device in the front-rear direction.
In FIGS. 6 and 8 of EP 0 874 382 the function of the switch is described. FIG. 8 shows the “ON” state of the switch. The elastic contact-point 11 for switch slides on the bottom surface of revolving contact points board 2 to make contact with the ring contact-point 8. As a result, the common contact-point 12 and the contact-point 11 for switch are electrically coupled via ring contact-point 8 to make up a state of switch ON.
It is a further general drawback with the device described in EP 0 874 382 that the contact-points 11,12,13,14 slide on the bottom surface of revolving contact points board 2, see for example FIGS. 4, 6 and 8. The sliding contacts are used both for detecting a rotation of the operation knob 3 and for providing the switch function. This will generally involve rebound. Therefore, the switch function can not be considered a high quality switch since it will suffer from rebound in its “ON” state. If such switch is an active part of the signal path in audio equipment, such as hearing aids, it will cause audible noise and clicks.
In addition, the sliding contacts will suffer from poor long term stability and a poor reliability.
U.S. Pat. No. 5,711,415 discloses a rotary electronic component with a push switch, wherein a single control knob can individually operate a rotary component portion and a push switch. The rotary electronic component comprises a rotary component portion with a rotary body rotatable in a fixed position, a knob shaft, a control knob fitted concentrically around the outer periphery of the knob shaft, a resilient portion disposed between the knob shaft and the inner periphery of the control knob, and a push switch portion. The rotary component portion is actuated by rotation of the control knob while the push switch portion is actuated by the radial displacement of the control knob. In particular, the push switch is located outside the control knob, which complicates assembly of the rotary electronic component as the push switch has to be firmly fixed to an underlying support, e.g. a printed circuit board (PCB). This also limits the possibilities for miniaturisation of the component described in U.S. Pat. No. 5,711,415.
It may be seen as an object of the present invention to provide a combined roller and switch suited for applications with very limited space available. In addition, contact elements of the switch should not rotate together with the roller member in order to make the switch function free from rebounds thus reducing noise.